Investigation of a Portable Wind Tunnel for Energy Harvesting

Current wind tunnels possess a large space volume and high manufacturing cost, which are not suitable for investigating micro energy harvesters. This paper aims to design and fabricate a small, portable and low-speed wind tunnel for energy harvesting. A wind tunnel structure was first designed, a finite element analyses is then utilized to obtain the airflow velocity and turbulence intensity at the testing section, and the influence of the structural parameters of the wind tunnel on the flow field performance is finally investigated to achieve better performance. An experimental prototype of the wind tunnel was fabricated to verify the simulation results. Results demonstrated that the distribution uniformity and average turbulence intensity at the test section decrease first and then increase with the increase of both the diffuser and contraction lengths. The rectifying and damping effect of the honeycomb increase with increasing porosity and thickness. When the diffuser and contraction lengths are 850 mm and 480 mm, respectively, a better distribution uniformity and a lower turbulence intensity can be achieved. Experimental results were in good agreement with the simulation values. The maximum airflow velocity can reach up to 24.74 m/s, and the minimum error was only 1.23%. The designed wind tunnel achieved low-speed, small, portable and stable functions. This work provides an important guidance for further investigating the piezoelectric energy harvesting.

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Modeling and Experiment of a V-Shaped Piezoelectric Energy Harvester

Shock and Vibration ◽

10.1155/2018/7082724 ◽

2018 ◽

Vol 2018 ◽

pp. 1-15 ◽

Cited By ~ 2

Author(s):

Yue Zhao ◽

Yi Qin ◽

Lei Guo ◽

Baoping Tang

Keyword(s):

Energy Harvesting ◽

Frequency Band ◽

Electromechanical Coupling ◽

Energy Harvester ◽

Structural Parameters ◽

Ambient Vibration ◽

Piezoelectric Bimorph ◽

Actual Structure ◽

Piezoelectric Energy ◽

Operation Frequency

Vibration-based energy harvesting technology is the most promising method to solve the problems of self-powered wireless sensor nodes, but most of the vibration-based energy harvesters have a rather narrow operation bandwidth and the operation frequency band is not convenient to adjust when the ambient frequency changes. Since the ambient vibration may be broadband and changeable, a novel V-shaped vibration energy harvester based on the conventional piezoelectric bimorph cantilevered structure is proposed, which successfully improves the energy harvesting efficiency and provides a way to adjust the operation frequency band of the energy harvester conveniently. The electromechanical coupling equations are established by using Euler-Bernoulli equation and piezoelectric equation, and then the coupled circuit equation is derived based on the series connected piezoelectric cantilevers and Kirchhoff's laws. With the above equations, the output performances of V-shaped structure under different structural parameters and load resistances are simulated and discussed. Finally, by changing the angle θ between two piezoelectric bimorph beams and the load resistance, various comprehensive experiments are carried out to test the performance of this V-shaped energy harvester under the same excitation. The experimental results show that the V-shaped energy harvester can not only improve the frequency response characteristic and the output performance of the electrical energy, but also conveniently tune the operation bandwidth; thus it has great application potential in actual structure health monitoring under variable working condition.

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Performance Evaluation of a Piezoelectric Energy Harvester Based on Flag-Flutter

Micromachines ◽

10.3390/mi11100933 ◽

2020 ◽

Vol 11 (10) ◽

pp. 933 ◽

Cited By ~ 3

Author(s):

Hassan Elahi ◽

Marco Eugeni ◽

Federico Fune ◽

Luca Lampani ◽

Franco Mastroddi ◽

...

Keyword(s):

Performance Evaluation ◽

Wind Tunnel ◽

Energy Harvesting ◽

Energy Harvester ◽

Maximum Output Power ◽

Research Work ◽

Maximum Output ◽

Operational Environment ◽

Subsonic Wind Tunnel ◽

Piezoelectric Energy

In the last few decades, piezoelectric (PZT) materials have played a vital role in the aerospace industry because of their energy harvesting capability. PZT energy harvesters (PEH) absorb the energy from an operational environment and can transform it into useful energy to drive nano/micro-electronic components. In this research work, a PEH based on the flag-flutter mechanism is presented. This mechanism is based on fluid-structure interaction (FSI). The flag is subjected to the axial airflow in the subsonic wind tunnel. The performance evaluation of the harvester and aeroelastic analysis is investigated numerically and experimentally. A novel solution is presented to extract energy from Limit Cycle Oscillations (LCOs) phenomenon by means of PZT transduction. The PZT patch absorbs the flow-induced structural vibrations and transforms it into electrical energy. Furthermore, the optimal resistance and length of the flag is predicted to maximize the energy harvesting. Different configurations of flag i.e., with Aluminium (Al) patch and PZT patch for flutter mode vibration mode are studied numerically and experimentally. The bifurcation diagram is constructed for the experimental campaign for the flutter instability of a cantilevered flag in subsonic wind-tunnel. Moreover, the flutter boundary conditions are analysed for reduced critical velocity and frequency. The designed PZT energy harvester via flag-flutter mechanism is suitable for energy harvesting in aerospace engineering applications to drive wireless sensors. The maximum output power that can be generated from the designed harvester is 6.72 mW and the optimal resistance is predicted to be 0.33 MΩ.

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Experimental study of turbulence intensity influence on wind turbine performance and wake recovery in a low-speed wind tunnel

Renewable Energy ◽

10.1016/j.renene.2017.03.034 ◽

2017 ◽

Vol 109 ◽

pp. 363-371 ◽

Cited By ~ 20

Author(s):

Miguel Talavera ◽

Fangjun Shu

Keyword(s):

Experimental Study ◽

Wind Tunnel ◽

Wind Turbine ◽

Turbulence Intensity ◽

Low Speed ◽

Turbine Performance ◽

Low Speed Wind Tunnel

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Energy Harvesting Performance of a Wing Panel for Aeroelastic Vibration

International Journal of Structural Stability and Dynamics ◽

10.1142/s0219455419501025 ◽

2019 ◽

Vol 19 (09) ◽

pp. 1950102 ◽

Cited By ~ 4

Author(s):

Xiaobiao Shan ◽

Haigang Tian ◽

Tao Xie

Keyword(s):

Energy Harvesting ◽

Output Power ◽

Structural Parameters ◽

Experimental Results ◽

Vibration Energy Harvesting ◽

Airflow Velocity ◽

Average Output ◽

Piezoelectric Patch ◽

Optimal Output ◽

Wing Panel

This paper focuses on the aeroelastic vibration energy harvesting performance of a wing panel. A nonlinear mathematical model of fluid-structure-electric coupling field was established based on the aeroelastic vibration equation and piezoelectric equation. Numerical analysis was performed to explore the influences of the airflow velocity and the piezoelectric material structural parameters on both the dynamic response and the energy harvesting performance. A small experimental wind tunnel and several prototypes of energy harvesters of the wing panel were designed and fabricated. The experimental results show that the vibration amplitude and output power of the wing panel increase with the airflow velocity; the average output power first increases until it attains the maximum values, and then decreases with the increase of the dimensionless length ([Formula: see text]/[Formula: see text] and the thickness of the piezoelectric patch. It shows that the theoretical and experimental results are in good agreement. The experimental optimal output power is 3[Formula: see text]mW at the airflow velocity of 12[Formula: see text]m/s, and the piezoelectric patch length, width and thickness of 40, 20 and 0.2[Formula: see text]mm, respectively. This work provides an effective theoretical and experimental basis for studying energy harvesting and vibration control of airfoil aircrafts.

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Development of Piezoelectric Energy Harvester System through Optimizing Multiple Structural Parameters

Sensors ◽

10.3390/s21082876 ◽

2021 ◽

Vol 21 (8) ◽

pp. 2876

Author(s):

Hailu Yang ◽

Ya Wei ◽

Weidong Zhang ◽

Yibo Ai ◽

Zhoujing Ye ◽

...

Keyword(s):

Power Generation ◽

Energy Harvesting ◽

Energy Harvester ◽

Structural Parameters ◽

Mechanical Energy ◽

Electrical Energy ◽

Cross Sectional ◽

Accelerated Pavement Testing ◽

Piezoelectric Energy ◽

Pavement Testing

Road power generation technology is of significance for constructing smart roads. With a high electromechanical conversion rate and high bearing capacity, the stack piezoelectric transducer is one of the most used structures in road energy harvesting to convert mechanical energy into electrical energy. To further improve the energy generation efficiency of this type of piezoelectric energy harvester (PEH), this study theoretically and experimentally investigated the influences of connection mode, number of stack layers, ratio of height to cross-sectional area and number of units on the power generation performance. Two types of PEHs were designed and verified using a laboratory accelerated pavement testing system. The findings of this study can guide the structural optimization of PEHs to meet different purposes of sensing or energy harvesting.

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Ceramic-Based Piezoelectric Material for Energy Harvesting Using Hybrid Excitation

Materials ◽

10.3390/ma14195816 ◽

2021 ◽

Vol 14 (19) ◽

pp. 5816

Author(s):

Bartłomiej Ambrożkiewicz ◽

Zbigniew Czyż ◽

Paweł Karpiński ◽

Paweł Stączek ◽

Grzegorz Litak ◽

...

Keyword(s):

Wind Tunnel ◽

Energy Harvesting ◽

Piezoelectric Material ◽

Lead Zirconate Titanate ◽

Bluff Body ◽

Fiber Composite ◽

Air Flow ◽

Linear Acceleration ◽

Test Rig ◽

Piezoelectric Energy

This paper analyzes the energy efficiency of a Micro Fiber Composite (MFC) piezoelectric system. It is based on a smart Lead Zirconate Titanate material that consists of a monolithic PZT (piezoelectric ceramic) wafer, which is a ceramic-based piezoelectric material. An experimental test rig consisting of a wind tunnel and a developed measurement system was used to conduct the experiment. The developed test rig allowed changing the air velocity around the tested bluff body and the frequency of forced vibrations as well as recording the output voltage signal and linear acceleration of the tested object. The mechanical vibrations and the air flow were used to find the optimal performance of the piezoelectric energy harvesting system. The performance of the proposed piezoelectric wind energy harvester was tested for the same design, but of different masses. The geometry of the hybrid bluff body is a combination of cuboid and cylindrical shapes. The results of testing five bluff bodies for a range of wind tunnel air flow velocities from 4 to 15 m/s with additional vibration excitation frequencies from 0 to 10 Hz are presented. The conducted tests revealed the areas of the highest voltage output under specific excitation conditions that enable supplying low-power sensors with harvested energy.

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Study on the Effect of Oval Tubes on Airflow Turbulence Characteristics in Wind Tunnel

Xibei Gongye Daxue Xuebao/Journal of Northwestern Polytechnical University ◽

10.1051/jnwpu/20203820303 ◽

2020 ◽

Vol 38 (2) ◽

pp. 303-308

Author(s):

Bo Zhao ◽

Cheng Fu ◽

Haitao Pei ◽

Daxiong Liao ◽

Bo Zhu

Keyword(s):

Heat Exchanger ◽

Wind Tunnel ◽

Turbulence Intensity ◽

Flow Direction ◽

Structural Parameters ◽

Simulation Method ◽

Experimental Result ◽

Turbulence Characteristics ◽

Tube Heat Exchanger ◽

Inflow Conditions

The flow Turbulence characteristics of finned oval tube heat exchanger used in wind tunnel were studied by using numerical simulation method. Firstly, the reliability of the numerical method was verified by the experimental results. And then the research was focused on the comparative analysis of the characteristics of turbulent flow downstream of heat exchanger under different inflow conditions, and the influence of the tubes number and fins spacing on the airflow turbulence and the flow field distribution downstream of heat exchanger were obtained too. The results indicate that oval tubes have a significant effect for improving the flow quality when incoming flow is inhomogeneous, and the velocity distribution behind heat exchanger tends to become uniform. Inflow conditions have a slight effect on the turbulence intensity behind heat exchanger, which mainly depends on the structural parameters of heat transfer tubes. The turbulence intensity decays very quickly in the flow direction. The value is reduced to 7.5% at the cross section 600 mm downstream of the heat exchanger inlet, which agrees well with the experimental result.

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